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Last month, PBS announced that Harper Lee's To Kill a Mockingbird was voted by viewers as "America's best-loved novel." But writer Aaron Sorkin told 60 Minutes that, when he began adapting the Southern classic for the Broadway stage, he wasn't afraid to tweak the cherished story.

"When you're adapting something, at some point you have to fall out of love with the book and make it something new," he told correspondent Steve Kroft.

To begin with, Sorkin wanted a new protagonist. He said that, in the novel, Scout is the central character, the person whose point of view tells the story and whose perspective changes through the book. But for his stage adaptation, he wanted to make it clear that Atticus Finch plays that role. To do that, Atticus couldn't be the same from beginning to end; he needed an initial flaw.

Sorkin also knew he couldn't ignore the six decades that have passed since Lee wrote the book. And that's when he realized—Atticus Finch already had an imperfection. It is a trait readers had historically seen as virtuous: his tendency to forgive people for their faults, including their racism. Sorkin sees that as a flaw in Atticus himself.

"I would be reading the book, and over and over again, Atticus is telling us in different ways that there is goodness in everybody, that you have to crawl around in someone else's skin before you can really know them," Sorkin tells Kroft in the video above. "He excuses racism a number of times."

Then, as Sorkin was working on the script last year, President Donald Trump made a statement in response to the white nationalist rally in Charlottesville, saying that there were " very fine people, on both sides."

Sorkin said the president's statement had a familiar ring.

"I wanted in the play for Atticus to be forced to wrestle with the question of, is there goodness in everybody?" Sorkin said. "Should these things be excused? So nearly every character in the play now challenges that point of view."

In the book, Sorkin said, Atticus is a moral guiding light for Scout and the other children. Now in the play, he struggles to answer: What makes a person moral?

The scene Sorkin excluded from "To Kill a Mockingbird"

Sorkin didn't just reexamine Atticus's unimpeachable reputation. This week on 60 Minutes, he told Kroft that he expanded the roles of two African American characters: Tom Robinson, the man a white woman accuses of rape, and Calpurnia, Atticus's longtime cook.

"In this story about racial tension, Jim Crow, injustice in the south, the only two African American characters have nothing to say on the matter," Sorkin said. "We understand now in 2018 that using African American characters as atmosphere in a story is offensive. Also in this story, it's a wasted opportunity."

Sorkin also scrutinizes a scene from the courthouse that appears in both the book and the 1962 movie, a scene that he said always made him teary—but doesn't hold up in today's times.

In the courthouse, the upper balcony was called the "colored section," the seating where non-whites were relegated. At the end of the trial, after his client is found guilty, Atticus turns around to leave and sees everyone in the balcony standing up in a gesture of respect to him.

"Those people in the balcony should be rioting in the streets," Sorkin said in the clip above. "They should be chanting, 'No justice, no peace.' They should be burning the courtroom down. But instead, they're standing up docile, in respect and gratitude to the white liberal who just lost the case."

Sorkin said the scene is a "liberal fantasy" and did not include it in the play.

How Jeff Daniels sees Atticus Finch

In preparing to play Atticus Finch, a role made famous by Gregory Peck's Academy Award-winning performance, actor Jeff Daniels told 60 Minutes that he did a lot of research. First, he reread To Kill a Mockingbird, then he read biographies on Harper Lee. He studied the Jim Crow south and researched sundown towns, all-white neighborhoods that keep themselves segregated by a combination of laws, intimidation, and violence.

After his research, he constructed his vision of Atticus Finch. "He's a guy that was caught in the middle," Daniels said in the clip above. "All around him is this blatant racism."

But Atticus doesn't do anything about it because he doesn't want to be labeled a race traitor and jeopardize his family's safety. He lets racism pass him by—until he takes Tom Robinson's case.

"Aaron's got a great line in there," Daniels said of Sorkin's script. "Atticus says, 'Tom Robinson's a man, honey. He's a full-grown man,' which is saying he's a human being. He's not a black man, not a colored man. He's a human being."

Jeff Daniels on "Mockingbird" for 2018

Daniels told Kroft his job as an actor is to bring Atticus Finch to life, not to focus on whether or not the play relates to modern day.

Still, he told Kroft in the clip above that the play is still timely.

"[Race] is engrained, embedded, entrenched in this country," Daniels said. "Whatever's going on now is just some of that stuff a couple of centuries ago. It was as alive then as it is now. And that's the unfortunate part."

To watch Steve Kroft's report on Broadway's To Kill a Mockingbird, click here.